Aluminum care

[chille51]

Hey all, as you may have seen on the "what did you do to your boat" thread, I recently put an all aluminum skip top on my Arima. It is not anodized or powder coated, it is bare 5052 aluminum. Given that I just got it, and it hasn't seen saltwater yet, I figure if there is a care regimen to keep it looking decent and more importantly limit corrosion, I might as well start now. The fabricator told me to just rinse it well after seeing salt and other than that leave it be and let it oxidize naturally to protect it, and that would certainly be easiest. Im already in the habit of rinsing down the boat and trailer with Salt Away.

On the other hand there are about a million wipe/spray/paint on products out there - Alumaguard, Sheila Shine, Sharkhide and a myriad of similar or Knock off products. I'm not looking to create work for myself, and it isn't really about looks - I know unfinished 5052 is never going to polish up like stainless. Just spent a decent chunk of change on this thing so want to take care of it.

Related question - when attaching things to it (Antenna mounts, lights etc.) And using stainless fasteners - just tef gel it and otherwise don't worry or...?

 

[brands51]

Tef gel should work, I use marine grade/metal free anti seize as most regular anti seize contains copper or other dissimilar metals.

I’ve been told stainless hardware for aluminum and that’s what I’ve been using.

 

[Reel Gone]

You can use neo washers to keep the head of the fastener from contacting the alum, they are alum rubber backed washers.

 

[ClintR]

Skim of sikaflex between aluminum and any stainless on my rig.

 

[chille51]

Thanks all, sounds like lots of options for the stainless to aluminum connection. Any thoughts one way or the other on the general upkeep?

 

[Brando]

Nylon washers work well for this application. And are cheap and available at hardware stores.

You could do a conversion coating on the aluminum but I have never tried it while bolted to a fiberglass boat. It involves a fairly strong acid and chromium coating. If the top is easily removed imo thats your best option.

Sharkhide or nyalic would be the next best choice.

Leaving it raw is fine too 5xxx series aluminum is all technically “marine grade” it will oxidize and dull over time. Red scotch brite pads work well to bring the shine back but you need to be aware they do leave some micro sanding scratches so going in the same direction to get a consistent finish is important and it’s quite labor intensive to do something of this size. Best to practice on a piece of scrap so you get the idea first.

General maintenance will be a good rinse after using. Salt away is a good option or just lots of fresh water. Aluminum is light and strong but quite soft when compared to stainless so it does scratch fairly easy.

 

[chille51]

Nylon washers work well for this application. And are cheap and available at hardware stores.

You could do a conversion coating on the aluminum but I have never tried it while bolted to a fiberglass boat. It involves a fairly strong acid and chromium coating. If the top is easily removed imo thats your best option.

Sharkhide or nyalic would be the next best choice.

Leaving it raw is fine too 5xxx series aluminum is all technically “marine grade” it will oxidize and dull over time. Red scotch brite pads work well to bring the shine back but you need to be aware they do leave some micro sanding scratches so going in the same direction to get a consistent finish is important and it’s quite labor intensive to do something of this size. Best to practice on a piece of scrap so you get the idea first.

General maintenance will be a good rinse after using. Salt away is a good option or just lots of fresh water. Aluminum is light and strong but quite soft when compared to stainless so it does scratch fairly easy.

Thanks Brando. I don't intent to pull it off the boat so whatever I do will be done in place. I'll look into the Sharkhide or Nyalic a little more - I thought I read that they are easily scratched, and tough to maintain the same finish with a repair. I don't think I'll mind the dulled aluminum look if that is the lowest maintenance - doesn't hitting it with a scotch brite pad remove the natural protective coating?

 

[Brando]

Thanks Brando. I don't intent to pull it off the boat so whatever I do will be done in place. I'll look into the Sharkhide or Nyalic a little more - I thought I read that they are easily scratched, and tough to maintain the same finish with a repair. I don't think I'll mind the dulled aluminum look if that is the lowest maintenance - doesn't hitting it with a scotch brite pad remove the natural protective coating?

Yes and no for the scotch brite. It will oxidize fairly quickly but have a more consistent finish again until you have to repeat the process. This is not a normal/annual maintenance. More like every 3+ seasons if you wanted to bring it back to its current state.

 

[InterMechanico]

My boat had shark hide applied when new (Oct.2019) and has been moored at Reed Point ever since. It seems to hold up really well from what I see, FWIW.

 

[chille51]

Yes and no for the scotch brite. It will oxidize fairly quickly but have a more consistent finish again until you have to repeat the process. This is not a normal/annual maintenance. More like every 3+ seasons if you wanted to bring it back to its current state.

It's not a totally uniform finish now... tubing is duller in spots than the plate. Also a few sharper edges on the rocket launchers I want to take down a bit. Do you figure the scotch brite treatment now + sharkhide immediately after that would be a reasonable way to start life off right for it?

 

[Brando]

It's not a totally uniform finish now... tubing is duller in spots than the plate. Also a few sharper edges on the rocket launchers I want to take down a bit. Do you figure the scotch brite treatment now + sharkhide immediately after that would be a reasonable way to start life off right for it?

That sounds like a good idea. I am not familiar with shark hides process but there may be a mild acid treatment first. If that’s the case I would do the scotch brite-acid-clear coat. Aluminum oxidizes very quickly so try to do the acid and clear in the same day.

 

[chille51]

Sounds like a plan. Seems like the Sharkhide I'll need to order off Amazon. Kind of surprised they will ship it actually.